For this type of apparatus, there is known an apparatus configured to detect adventitious sounds, i.e., sounds that are different from normal breath sounds, wherein the adventitious sounds are included in breath sounds of a living body detected by an electronic stethoscope or the like. For example, Patent Literature 1 discloses a technology/technique in which an amplitude spectrum, a phase spectrum, and a power spectrum are calculated by a Fast Fourier Transform (FFT) process and in which the normal breath sounds and the continuous sounds are distinguished by determining whether or not a local variance value of the power spectrum exceeds a threshold value. Moreover, Patent Literature 2 discloses a technology/technique in which a peak that can be determined to be erroneously detected is removed after the detection of a peak position on an autocorrelation function, to thereby detect the continuous sounds.